“We had good soil moisture to incorporate, but our pre-emergence treatments did not receive any rainfall for 12 days. So they lay there for 12 days before they were activated. At this site, we had two tillage options, including a pre-emergence application and the roto-tiller. We had two herbicide options — one was no herbicide and the other was Reflex applied at 1 pint per acre. At 14 and 28 days after planting, the preplant incorporated treatment was more effective than the pre-emergence treatment.”

At the third site, also in Macon County, there was no soil moisture, says Kichler. Treatments included no herbicide and Reflex at 1 pint per acre. Tillage included a pre-emergence application of Reflex and also the L-tine rototiller. There were no significant differences between the two applications due to the fact that there was no moisture to aid in the emergence of Palmer amaranth.

“In an irrigated situation, the pre-emergence applications were most effective, but if you have a grower who is concerned about crop injury, a shallow incorporation will reduce control by 9 percent. In a dryland situation with moist soil to incorporate your residual herbicide, but no activating rainfall for your pre-emergence, the preplant incorporated with shallow incorporation treatment will be more effective than the pre-emergence application.

“And if you’re in a bone-day situation, it really doesn’t matter about your application method because Palmer amaranth probably won’t emerge anyway until it rains. The roto-tiller was most effective and the disk harrow was least effective as far as tillage implements go.”

phollis@farmpress.com